History of truck bought brand new drive it to tire shop put 35's on it drive it home ppei was on door step 60 miles on truck deleted tuned on big tune. Now hand calculated 19-20 on Hywy all day dic saying 23. Now 89,000 later truck is getting 13-14 at best hand calculated and dic . So I've done everything I can think of fuel filters deleted stock one. Maf sensor air filters ect. No change air pressure in tires 65. So I got a cp3 coming be here tomorrow and my trans is acting up so I'm dropping it and building it. My question is could my tranny been hurt longer than I thought and causing bad mileage or my pump? 15.5 lml oh has a fass on it too. I sas the truck so locking hubs up front and still mileage is same I'm floored with what's going on
